Abstract
Background
Primary biliary cholangitis (PBC) is a chronic, progressive autoimmune disease characterized by the destruction of intrahepatic biliary epithelial cells, progressive fibrosis, and the expression of anti-mitochondrial antibodies. Although ursodeoxycholic acid (UDCA) can significantly improve liver biochemical parameters and delay disease progression as a first-line treatment, 40% of patients still have a poor response to UDCA treatment. Inflammation involving different regions of the hepatic lobule may be related to the therapeutic effect of UDCA. The aim of this study is to investigate the relationship between liver inflammation zones and UDCA treatment response in PBC patients, and to further analyze the predictive value of liver lobular zones for treatment response.
Methods
This is a single-center retrospective cohort study. A total of 121 PBC patients diagnosed in the Second Affiliated Hospital of Kunming Medical University from December 2014 to March 2024 were enrolled. Drawing on the Rappaport hepatic acinar zoning model and combining with the Bahar Halpern theory, the liver lobules were divided into three regions. The relationship between different divisions of liver lobules involved in PBC and the therapeutic effect of UDCA was studied, and the Nakanuma grading system was applied to evaluate the histological features. logistic regression analysis was used to investigate the association between lobular regions involved and non-response to UDCA treatment.
Results
In univariate analysis, gender, jaundice, ascites and lesion involvement were statistically significant (P < 0.05), and these factors may be independent risk factors for non-response to UDCA.Lesions zone 3 involvement (the area around the central vein) were significantly associated with a poor response to UDCA treatment (OR: 3.632, CI95%: 1.130-11.677, P = 0.030). In addition, the presence of ascites at baseline was also an important risk factor for poor response to UDCA treatment (OR: 5.475, CI95%: 1.221–24.551, P = 0.026).
Conclusions
The pathological changes involving zone 3 of the hepatic lobule may be an important pathological marker for predicting the poor response of PBC patients to UDCA.
Keywords: Primary biliary cholangitis, Ursodeoxycholic acid, Hepatic lobular division, Histopathology, Treatment response
Introduction
Primary Biliary Cholangitis (PBC) is a chronic, progressive autoimmune disease. It is characterized by selective destruction of intrahepatic bile duct epithelial cells, progressive fibrosis, and expression of anti-mitochondrial antibody (AMA-M2) [1–3]. With the deepening of the understanding of PBC and the development and application of autoantibody detection technology, the incidence of PBC is increasing worldwide. The incidence rate of PBC in China ranks second highest in the Asia-Pacific region (34.2 per 100,000 population) [4] and seventh globally [5, 6]. At present, UDCA as the first-line treatment of PBC, with a dose of 13–15 mg/ (kg·d), can significantly improve liver biochemical indexes, delay histological progression and improve patient survival rate [7]. However, approximately 40% of patients do not have an adequate response to UDCA treatment. These patients are more prone to hepatic complications such as ascites, variceal bleeding, and hepatic encephalopathy [8]. How to identify UDCA-refractory PBC patients early and give individualized treatment is the difficulty of current clinical research.
Previous studies have shown that the pathological progression of PBC usually starts from inflammation in the portal area, gradually progresses to bile duct injury, fibrosis, and finally develops to cirrhosis [9]. According to the direction of liver metabolism, some scholars have divided the liver into three regions: the portal area and the surrounding hepatocyte area (zone 1), the central venous surrounding hepatocyte area (zone 3), and the transition area between the two (zone 2) [10], reflecting the first, second and third masses of blood oxygen and nutrients respectively. Different metabolic characteristics and blood flow conditions also determine the sensitivity of each region to specific pathological states. Whether the progression of PBC lesions to the central lobular vein is related to the non-response to UDCA has not been reported in the literature, which needs to be further verified. This study aims to explore the relationship between liver inflammation zones and UDCA treatment response in PBC patients, and further analyze the predictive value of liver lobular zones for treatment effect [11].
Patients and methods
Study patients
This study was a single-center retrospective cohort study conducted in the Second Affiliated Hospital of Kunming Medical University. A total of 455 patients diagnosed with PBC from December 2014 to March 2024 were collected through the electronic medical record database. On the basis of inclusion and exclusion criteria, 121 patients were enrolled (Fig. 1). The study followed the ethical guidelines of the Declaration of Helsinki and was approved by the Ethics Committee of the Second Affiliated Hospital of Kunming Medical University (approval number: KMMU2025MEC155). Because this study was a retrospective analysis and the data were routine clinical data, informed consent from the patients was waived.
Fig. 1.
Participant selection flowchart
Diagnostic criteria for PBC
According to the guidelines of the American Association for the Study of Liver Diseases (AASLD) and the European Association for the Study of Liver Diseases (EASL), the diagnostic criteria for PBC include: (1) Biochemical abnormalities reflecting cholestasis (such as elevated ALP and GGT); (2) Positive serum AMA/AMA-M2 or positive other PBC-specific autoantibodies; (3) Liver biopsy showed non-suppurative destructive cholangitis and destruction of small bile ducts.
Inclusion and exclusion criteria
Inclusion criteria: (1) Comply with the "Guidelines for the Diagnosis and Treatment of Primary Biliary Cholangitis (2021)";(2) UDCA 13-15 mg /kg/d was taken orally for ≥6 months from the diagnosis; (3) No other drugs affecting liver and kidney function in the past 6 months;(4) No previous history of liver surgery;(5) Complete clinical data.
Exclusion criteria: (1) Combined with other types of liver diseases (primary sclerosing cholangitis, Budd-Chia-Chih syndrome, autoimmune hepatitis - primary biliary cholangitis (AIH-PBC) overlap syndrome, viral hepatitis, alcoholic hepatitis, intrahepatic and extrahepatic biliary obstruction); (2) Liver biopsy was not performed.(3) Through a case-by-case review of patient medication history using the hospital’s electronic medical records and prescription system, any patients who had previously used fibrates (e.g., bezafibrate/fenofibrate), OCA, or other second-line PBC medications were excluded.
Assessment of biochemical response and outcome definition
This study employed the Paris II criteria to evaluate the biochemical response to UDCA treatment [12, 13]. The primary endpoint was defined as the biochemical response status at 12 months after initiating UDCA therapy. UDCA non-response was specifically defined as meeting any one of the following three biochemical criteria at 12 months after treatment [14, 15]: (1) alkaline phosphatase > 1.5 times the upper limit of normal; (2) aspartate aminotransferase > 1.5 times the upper limit of normal; (3) total bilirubin > 1 mg/dL. Patients meeting any of these criteria were classified into the non-response group, while the remaining patients were classified into the response group.
Data collection
The basic data of patients were collected through the electronic medical record system, including demographic characteristics, medical history, clinical symptoms, and laboratory indicators (such as liver and kidney function, blood routine, etc.). The patients who used UDCA for the first time were defined as primary UDCA users (F-UDCA).
Pathological reading
Liver samples from all patients were obtained by percutaneous ultrasound-guided 16-gauge needle biopsy, and tissue sections were stained with hematoxylin and eosin (H&E).According to the Rappaport hepatic acinar zoning model and combined with the Bahar Halpern theory, the hepatic lobules are divided into three regions: zone 1 (periportal vein area, PP area); Zone 2 (transitional zone) and zone 3 (pericentral zone, PC zone). The Nakanuma grading system was used to assess histological features, including fibrosis, bile duct loss (BDL), and rhodanine-positive particle deposition. We used specific histological scoring criteria for liver fibrosis (F0–F4). Among them, F0 is defined as no fibrosis or only portal fibrosis without fibrous septum formation; F1 as portal fibrosis with a small number of short fibrous septa; F2 as bridging fibrous septum formation without significant architectural distortion; F3 as extensive bridging fibrosis with marked architectural distortion; and F4 as cirrhosis. Stages F0 and F1 were defined as the low-fibrosis group, and stages F2 and F3 as the high-fibrosis group. The pathological sections were reviewed by two subspecialists in liver pathology independently to ensure the objectivity and accuracy of the assessment.
Data analysis
SPSS 26.0 software was used for data analysis, and the significance level was set at 0.05. The median (quartile) or mean (standard deviation) was used to represent the data of measurement data. Categorical variables are expressed as frequencies (percentages). Independent sample t test or Mann-Whitney U test was used for comparison between groups. logistic regression analysis was used to explore the relationship between hepatic lobular division and UDCA treatment response.
Result
Baseline characteristics of the study population
A total of 121 PBC patients were enrolled, with a median age of 53 years (43.5–58.5 years), and 101 patients were female, accounting for 83.5%. In this study, 111 patients (91.7%) underwent puncture before UDCA treatment. Twenty patients (16.5%) had hypertension, 27 patients (22.3%) had thyroid disease, 38 patients (31.7%) had jaundice, and 16 patients (13.3%) had a history of ascites. Pathological sections showed that 83 cases (68.6%) of inflammation involved the zone 2, and 34 cases (28.1%) involved the zone 3.
In evaluating the histological features of liver biopsy in PBC patients using the Nakanuma grading system, we found that all patients collected had features of fibrosis, but the degree of fibrosis was different, and the corresponding response to UDCA treatment was also different. (Fig. 2)
Fig. 2.
This image shows MASSON staining, and collagen fibers are stained green. A The fibrosis was confined to the portal area and did not spread to the periphery; B Liver fibrosis gradually involves interlobular inflammation; C The fibrosis gradually aggravated, and the fibrosis in the interlobular portal areas connected to each other to form bridging necrosis; D Liver fibrosis has developed into intralobular, and the hepatocytes around the central veins are replaced by collagen fibers.
Relationship between response to UDCA treatment and hepatic lobular zoning
According to the response to UDCA treatment, the patients were divided into two groups: the response group (ALP ≤ 1.67 times of the upper limit, and/or TBil < or equal to 17.1 umol/L) had 55 patients, accounting for 45.5%. There were 66 cases in the non-response group (ALP > 1.67 times of the upper limit, and/or TBil > 17.1 umol/L). There was no significant difference in age and gender distribution between the two groups (P > 0.05). And there was no significant difference between the two groups in whether puncture before UDCA treatment (P > 0.05). At baseline, the proportion of lesions involving zone 3 was significantly higher in the non-response group than in the response group (P < 0.05), and ascites and jaundice symptoms caused by PBC were also frequently seen in the non-response group (P < 0.05)(Table 1). After 6 to 12 months of UDCA treatment, TB, total bile acid and ALP in non-response group were also significantly higher than those in response group (P < 0.05). (Fig. 3)
Table 1.
Baseline characteristics of the biochemical response in patients with PBC
| Characteristics | Total | Status of response | t/z/χ² | P-value | |
|---|---|---|---|---|---|
| Responders | Non-responders | ||||
| (n = 121) | (n = 55;45.5%) | (n = 66;54.5%) | |||
| Age(Q1-Q3, years) | 53(43.5–58.5) | 54(42-59.5) | 53(45-57.3) | -0.716 | 0.474 |
| Sex, n% | 6.262 | 0.012 | |||
| male | 20(16.5) | 4(7.3) | 16(24.2) | ||
| female | 101(83.5) | 51(92.7) | 50(75.8) | ||
| BMI(Q1-Q3, kg/m2) | 22.4(21.6–22.7) | 22.4(21.9–22.9) | 22.4(21.2–22.5) | -0.484 | 0.628 |
| Puncture before treatment, n% | 111(91.7) | 48(87.3) | 63(95.5) | -1.621 | 0.105 |
| Hypertension, n% | 20(16.5) | 12(21.8) | 8(12.1) | 2.045 | 0.153 |
| Thyroid history, n% | 27(22.3) | 13(23.6) | 14(21.2) | 0.102 | 0.75 |
| Jaundice, n% | 38(31.7) | 8(14.8) | 30(45.5) | 12.885 | <0.001 |
| Ascitic fluid, n% | 16(13.3) | 3(5.6) | 13(19.7) | 5.140 | 0.023 |
| Total bilirubin(Q1 ~ Q3, µmol/L) | 20.1(13.9–38.8) | 13.9(11.5–19.6) | 34.6(19.2–67.0) | -6.653 | <0.001 |
| Total bile acids(Q1 ~ Q3, µmol/L) | 26.9(7.6–81.9) | 11.4(3.9–28.3) | 54.6(17.2-128.1) | -4.924 | <0.001 |
| Alkaline phosphatase (Q1 ~ Q3, U/L) | 252.0(131.0-477.5) | 164.0(97.0-263.0) | 360.5(221.0-562.0) | -4.875 | <0.001 |
| Zone of involvement, n% | |||||
| Zone1 | 121(100) | 66(100) | 55(100) | 0.000 | 1.000 |
| Zone2 | 83(68.6) | 34(61.8) | 49(74.2) | 2.150 | 0.143 |
| Zone3 | 34(28.1) | 8(14.5) | 26(39.4) | 9.168 | 0.002 |
| Fibrosis stages | 14.433 | 0.002 | |||
| F0 | 6(5) | 4(7.3) | 2(3.0) | ||
| F1 | 39(32.2) | 23(41.8) | 16(24.2) | ||
| F2 | 49(40.5) | 24(43.6) | 25(37.9) | ||
| F3 | 27(22.3) | 4(7.3) | 23(34.8) | ||
Continuous variables were summarized using medians and interquartile ranges (IQR: Q1–Q3)
BMI body mass index
Fig. 3.
The relationship between changes in total bilirubin levels and characteristics of pathological involvement zones in PBC patients
On review of the pathological slides, lesions were more severe and involved more zones in the nonresponse group than in the response group. In the non-response group, the proportion of liver fibrosis was higher, bile duct disappearance and bile duct reaction were more severe. In the response group, Fig. 4 showed a florid change in the small bile ducts in the portal area, and a small focal aggregation of inflammatory cells was seen in zone 2. In the case of the non-response group, Fig. 5 showed that the lesions were widely involved in zone 1, 2 and 3, fibrosis was observed in the portal area, interface inflammation was mild, small bile ducts disappeared and bile duct reaction was observed.
Fig. 4.
Shows cases in the UDCA response group. A According to Rappaport's hepatic acinar partition model combined with Bahar Halpern's theory, the hepatic lobule was divided into three regions. In this case, the lesions involved zone 1 and zone 2. B CK7 staining: small bile ducts in the portal area were outlined by immunohistochemistry. C In zone 1 (portal area), the lymphocytes and plasma cells gathered around the small bile ducts, showing a florid appearance
Fig. 5.
This figure shows cases in the UDCA non-response group. A According to Rappaport's hepatic acinar partition model combined with Bahar Halpern's theory, the hepatic lobule was divided into three regions. The lesions involved zones 1,2 and 3 simultaneously, and fibrosis was observed in zone 1. B CK7 staining: cholangialized hepatocytes were outlined by immunohistochemistry, and small bile ducts in the portal area were absent. C Infiltration and aggregation of lymphocytes and plasma cells were observed around zone 3 (central vein)
Zone involvement and UDCA response by fibrosis stage
We have supplemented the data on fibrosis stage and the rate of UDCA non-response among patients: F0: 2(3.0%); F1: 16(24.2%); F2: 25(37.9%); F3: 23(34.8%). Statistical testing indicated a significant difference in the rate of UDCA non-response across fibrosis stages (P=0.002). Subgroup analysis showed that in patients with low fibrosis stages, the extent of pathological involvement was not clearly associated with UDCA treatment response. However, in patients with advanced disease (high-fibrosis group), involvement of the third zone was significantly associated with UDCA non-response (P=0.030). (Table 2)
Table 2.
Zone involvement and UDCA response by fibrosis stage
| Characteristics | Low-fibrosis | High-fibrosis | ||||||
|---|---|---|---|---|---|---|---|---|
| Total | Responders | Non-responders | P | Total | Responders | Non-responders | P | |
| (n = 45) | (n = 28) | (n = 17) | (n = 76) | (n = 27) | (n = 49) | |||
| Zone of involvement, n(%) | ||||||||
| Zone1 | 45(100) | 28(100) | 17(100) | 76(100) | 27(100) | 49(100) | ||
| Zone2 | 22(48.9) | 13(46.4) | 9(52.9) | 0.672 | 61(80.3) | 21(77.8) | 40(81.6) | 0.686 |
| Zone3 | 11(24.4) | 4(14.3) | 7(41.2) | 0.042 | 23(30.3) | 4(14.8) | 19(38.8) | 0.030 |
Binary logistic regression model analysis
By univariate logistic regression analysis, we found that male (OR = 0.245, CI95%: 0.077–0.784,P = 0.018) was a protective factor for non-response to UDCA. However, jaundice (OR = 4.792, CI95%: 1.961–11.710, P = 0.001), ascites (OR = 4.170, CI95%: 1.122–15.499, P = 0.033) and the involvement of three areas (OR = 3.819, CI95%: 1.556–9.370, P = 0.003) were significantly different between the two groups. were statistically significant (P < 0.05). These factors may be independent risk factors for non-response to UDCA. To enhance the generalizability of the results, we further performed multivariate binary logistic regression analysis to assess the impact of different covariates. We designed three models, and similar results were obtained in model C after adjusting for variables such as age, sex, puncture before UDCA treatment, BMI, hypertension, thyroid disease, jaundice, ascites, total bile acids, total bilirubin, alkaline phosphatase, and lesion partition as required. Specifically, ascites (OR: 5.475, CI95%: 1.221–24.551, P = 0.026) and lesions affecting zone 3 (OR: 3.632, CI95%: 1.130-11.677, P = 0.030) were identified as risk factors for poor response to UDCA. These findings suggest that we need to pay more attention to these patients and pay attention to their clinical characteristics during treatment with UDCA. (Table 3).
Table 3.
Univariate and multivariate logistic regression analysis of the response to UDCA in PBC patients
| Characteristics | Univariate analysis | Multivariate analysis | ||||||
|---|---|---|---|---|---|---|---|---|
| ModelA | ModelB | ModelC | ||||||
| OR(95%CI) | P | OR(95%CI) | P | OR(95%CI) | P | OR(95%CI) | P | |
| Age | 1.011(0.977–1.048) | 0.525 | 1.009(0.971–1.049) | 0.653 | 0.992(0.947–1.039) | 0.720 | 1.002(0.953–1.053) | 0.950 |
| Sex(Female) | 0.245(0.077–0.784) | 0.018 | 0.243(0.072–0.822) | 0.023 | 0.138(0.032–0.597) | 0.008 | 0.168(0.033–0.868) | 0.033 |
| BMI | 1.042(0.915–1.188) | 0.533 | 1.049(0.908–1.211) | 0.517 | 1.083(0.929–1.262) | 0.308 | 1.046(0.890–1.231) | 0.584 |
| Puncture before treatment | 3.062(0.752–12.465) | 0.118 | 2.628(0.592–11.66) | 0.204 | 1.469(0.289–7.471) | 0.643 | 1.348(0.243–7.490) | 0.733 |
| Hypertension | 0.494(0.186–1.314) | 0.158 | 0.346(0.100-1.198) | 0.094 | 0.445(0.114–1.732) | 0.243 | ||
| Thyroid history | 0.870(0.369–2.050) | 0.750 | 0.933(0.333–2.616) | 0.896 | 1.236(0.399–3.826) | 0.713 | ||
| Jaundice | 4.792(1.961–11.710) | 0.001 | 5.147(1.847–14.338) | 0.002 | 2.211(0.640–7.643) | 0.210 | ||
| Ascitic fluid | 4.170(1.122–15.499) | 0.033 | 5.777(1.345–24.814) | 0.018 | 5.475(1.221–24.551) | 0.026 | ||
| Total bilirubin | 0.972(0.954–0.990) | 0.003 | 0.997(0.985–1.008) | 0.566 | ||||
| Total bile acids | 0.993(0.987–0.998) | 0.005 | 0.998(0.992–1.004) | 0.450 | ||||
| Alkaline phosphatase | 0.995(0.993–0.998) | 0.000 | 0.996(0.994–0.999) | 0.003 | ||||
| Zone of involvement | ||||||||
| Zone1 | 0.833 | 0.318 | ||||||
| Zone2 | 1.780(0.820-3.8653) | 0.145 | 1.271(0.536–3.014) | 0.586 | 1.276(0.487–3.339) | 0.620 | 1.241(0.424–3.627) | 0.424 |
| Zone3 | 3.819(1.556–9.370) | 0.003 | 3.202(1.211–8.465) | 0.019 | 3.475(1.164–10.372) | 0.026 | 3.632(1.130-11.677) | 0.030 |
ModelA: Age, Sex, BMI, Puncture before treatment, involving two zones, involving three zones
ModelB: Age, Sex, BMI, Puncture before treatment, hypertension, history of thyroid, jaundice, history of ascites, involvement of two zones, involvement of three zones
ModelC: Age, Sex, BMI, Puncture before treatment, hypertension, history of thyroid, jaundice, history of ascites, total bilirubin, total bile acid, alkaline phosphatase, involved two zones, involved three zone
Discussion
Zone 3 (the pericentral region) is a critical area of metabolic zonation, more specifically involved in zonated features such as drug/lipid metabolism, gluconeogenesis, and bile acid synthesis/transport [16–19]. In patients with PBC, lesions in zone 3 often manifest as “inflammatory cell infiltration” (e.g., neutrophils and lymphocytes) and “bile duct epithelial cell damage. This study found that patients with zone 3 lesions showed more significant fibrosis and bile duct injury (BDL) in pathological sections, which was consistent with the high grade lesions in the Nakanuma grading system [20]. Previous studies have pointed out that the inflammatory process of PBC usually starts from the portal area (zone 1), and then gradually spreads to the transitional area (zone 2) and the pericentral venous area (zone 3) [11]. Patients with zone 3 lesions are often in a “decompensated state,” which may indicate advanced disease. The present study further confirmed this theory: patients with zone 3 lesions had a higher Nakanuma grade, indicating more severe liver damage. This study revealed that when the lesion involved the third area of the liver lobule (the pericentral venous area), the patients had a poor response to UDCA treatment. This finding was consistent with the results of multiple logistic regression analysis (OR: 3.632, CI95%: 1.130-11.677, P = 0.030). These results suggest that lesions in region 3 of the liver lobule may be closely related to the pathological progression and treatment response of PBC. Lesions in zone 3 May affect the therapeutic effect of UDCA through the following mechanisms: Aggravation of cholestasis: Zone 3 is a key area of bile secretion, and lesions may lead to blocked biliary excretion [21], thereby reducing the efficacy of UDCA. Enhanced inflammatory response: lesions in zone 3 are usually accompanied by a more intense inflammatory response, which may weaken the inhibitory effect of UDCA on inflammation [22, 23]. Accelerated fibrosis progression: advanced fibrosis is closely related to poor response to UDCA treatment [24], and patients with zone 3 lesions have more fibrosis, which may limit the efficacy of UDCA.
As a key indicator of disease progression in PBC patients, ascites is closely related to liver decompensation and portal hypertension. The presence of ascites is associated with reduced patient survival and is a key factor for initiating alternative therapies, such as obeticholic acid, or for evaluating liver transplantation [25]. Meanwhile, patients with ascites at baseline had poor response to UDCA treatment (OR: 5.475, CI95%: 1.221–24.551, P = 0.026). The relationship between ascites and poor response to UDCA treatment may be achieved through the following mechanisms: Portal hypertension: the presence of ascites implies the presence of portal hypertension, which may lead to hepatic hemodynamic disorder and affect the metabolism and distribution of UDCA; Hepatic decompensation: the hepatic synthesis function and detoxification ability of patients with ascites are significantly decreased, which may limit the efficacy of UDCA [26]; Aggravated inflammatory response: The inflammatory response of patients with ascites is usually more active, which may weaken the inhibitory effect of UDCA on inflammation [21, 22].
We have supplemented the discussion as follows: Liver fibrosis is a core pathological feature of PBC progression, driven jointly by periductal fibroblasts and hepatic stellate cells, and forms a vicious cycle with abnormal bile acid metabolism [27, 28]. Consistent with existing literature, the rate of UDCA non-response significantly increased with the severity of liver fibrosis [12, 29]. Subgroup analysis suggests that patients with high fibrosis and involvement of the third zone should be regarded as a high-risk group for UDCA non-response, and closer monitoring and earlier consideration of combination therapy are recommended.
Logistic regression analysis indicated that compared to males, females were more likely to achieve a response to UDCA treatment (OR = 0.168, 95%CI: 0.033–0.868, P = 0.033). Jaundice is an important marker of cholestasis in PBC patients, and its presence may indicate more severe liver damage. Patients with jaundice had a worse response to UDCA treatment (OR = 2.211, 95% CI: 0.640–7.643, P = 0.210). In addition, as an autoimmune disease, a considerable number of PBC patients have thyroid-related diseases at the time of initial diagnosis, and hypothyroidism may affect the efficacy of UDCA, so thyroid hormone replacement therapy is required at the same time [23]. In this study, a total of 27 patients had thyroid related diseases at baseline, but due to our small sample size, no significant statistical difference was obtained.
The sample size of this study is limited, and the median follow-up period is relatively short, resulting in an insufficient number of hard endpoint events such as liver transplantation and liver-related death. Therefore, the association between Zone 3 histological features and long-term patient prognosis could not be analyzed. Future validation in larger prospective cohorts with longer follow-up periods is warranted. Although this study revealed key predictors, it is likely to be subject to selection bias due to its single-center, retrospective design, and therefore needs to be validated by a multicenter prospective study. At the same time, due to the small sample size, some subgroup analyses (e.g., age, thyroid disease) failed to reach statistical differences, which may affect the generalizability of the conclusions. Furthermore, although the vast majority of patients (91.7%) underwent liver biopsy at initial diagnosis, minimizing potential treatment interference, the timing was not fully uniform as a small number of biopsies were performed after UDCA initiation. Sensitivity analysis suggested these cases had limited influence on the overall findings; however, heterogeneity in biopsy timing may still introduce some uncertainty in assessing its relationship with UDCA response. Future studies should adopt a prospective design with a standardized pre-treatment biopsy window to ensure consistent histological assessment. In addition, the pathological assessment itself is subjective, and despite the use of double-blind reading, the definition of liver lobular zoning still relies on the experience of pathologists, which may introduce subjective bias. In the future, the combination of AI-assisted analysis may improve the objectivity and accuracy of liver lobular zoning assessment.
Conclusion
By combining the analysis of pathological zoning and clinical features, this study reveals that in patients with PBC, lesions involving zone 3 of the liver lobules on early liver biopsy may indicate a high risk of poor response to UDCA treatment. This finding suggests that clinicians should shorten the follow-up interval and consider combination regimens, such as UDCA plus obeticholic acid [30] or the addition of immunosuppressive agents and fibrates (e.g., fenofibrate and bezafibrate) [31]. Given the lack of clear biomarkers to identify patients who do not respond well to UDCA and who may benefit from the early introduction of second-line therapy, liver biopsy not only plays an important role in risk stratification of PBC, but also is an effective means of assessing the efficacy of UDCA.
Acknowledgements
Not applicable.
Authors’ contributions
Author contributions: Huanqiao Zhong was responsible for data curation, investigation, and writing; Mengyao Zheng and Sidi Li were responsible for project administration; Chunmei Zhao, Hongtao Lei, and Yan Wang were responsible for visualization; Qun Wei was responsible for validation; Tianyun Wang was responsible for software; Zhiyan Ou was responsible for formal analysis; Ning Li was responsible for supervision; Yaoyao was responsible for data curation; Xiang Kui was responsible for conceptualization, methodology, and funding acquisition; Xiang Kui, Hongtao Lei, and Yan Wang were responsible for review and editing;
Funding
The "Talent Echelon Construction" Training Project of the Second Affiliated Hospital of Kunming Medical University (Project No. RCTDXK-202301);Key Research and Development Program of Science and Technology Department of Yunnan Province, No.202403AC100023; Kunming Medical University First-class Discipline Team (Superior Team) Construction Project, No. 2024XKTDYS04. Construction Project of Key Specialty Base for Standardized Training of Resident Physicians in Yunnan Province in 2024.
Data availability
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
Declarations
Ethics approval and consent to participate
The study followed the ethical guidelines of the Declaration of Helsinki and was approved by the Ethics Committee of the Second Affiliated Hospital of Kunming Medical University. The requirement for informed consent was waived by Ethics Committee of the Second Affiliated Hospital of Kunming Medical University (KMMU2025MEC155) due to retrospective nature of study.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
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Contributor Information
Xiang Kui, Email: kuixiang@kmmu.edu.cn.
Hongtao Lei, Email: hongtaolei@qq.com.
Yan Wang, Email: wangyan@kmmu.edu.cn.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.